knot [OE] The words knot and knit, both Old English, are closely related. Something travelling fast might be described as going at a rate of knots [L19th]. A knot here is a measure of speed, equivalent to one nautical mile an hour. In the days of sailing ships a line with knots tied at fixed intervals and a float at the end was run out into the sea over a certain time to gauge the ship’s speed. If the line unwound very rapidly, with each knot appearing in quick succession, then the ship was going ‘at a rate of knots’. See also natty.